Aβ_(1~42)对阿尔茨海默病小鼠PI3K/PKB信号通路的影响

Effect of Aβ_(1~42) on PI3K/PKB signaling pathway in Alzheimer′s disease mice

目的探讨Aβ_(1~42)对阿尔茨海默病(AD)小鼠磷脂酰肌醇3激酶/蛋白激酶B(PI3K/PKB)信号通路的影响。方法雄性小鼠侧脑室注射链脲佐菌素制备AD模型,随机分为:假手术组、模型组、Aβ_(1~42)低剂量(0.015 mg/kg)组、Aβ_(1~42)中剂量(0.050 mg/kg)组、Aβ_(1~42)高剂量(0.150 mg/kg)组、胰岛素组。跳台实验检测小鼠认知功能;酶联免疫吸附试验(ELISA)检测各组小鼠海马胰岛素受体(InR)的含量;Western印迹法检测小鼠磷酸化蛋白激酶B(p-PKB)、磷酸化糖原合成酶激酶(p-GSK)-3β和磷酸化Tau蛋白(p-Tau)的表达量。结果与假手术组比较,模型组练习错误和记忆错误次数增多、潜伏期缩短(P<0.05);与模型组比较,Aβ_(1~42)不同剂量组练习和记忆错误次数增加、潜伏期缩短(P<0.05),胰岛素组练习和记忆错误次数减少、潜伏期增加(P<0.05)。与假手术组比较,模型组InR表达量降低(P<0.05)。与模型组比较,Aβ_(1~42)不同剂量组InR表达量降低(P<0.05);胰岛素组InR表达量升高(P<0.05)。与假手术组比较,模型组p-PKB、p-GSK-3β蛋白表达量降低,p-Tau表达量升高(P<0.05)。与模型组比较,Aβ_(1~42)不同剂量组p-PKB、p-GSK-3β蛋白表达量降低,p-Tau表达量升高(P<0.05);胰岛素组p-PKB、p-GSK-3β的表达量升高,p-Tau表达水平降低(P<0.05)。结论Aβ_(1~42)能够产生神经毒性,诱导小鼠认知功能障碍,其机制可能为干扰PI3K/PKB信号通路传导,下调InR表达,抑制PKB和GSK-3β磷酸化,使AD小鼠Tau蛋白磷酸化水平增加,导致认知功能障碍。

Objective To explore the effect of Aβ_(1~42)on PI3K/PKB signaling pathway in Alzheimer′s disease(AD)mice.Methods The male Sprague Dawley mice were injected with streptozotocin into the lateral ventricle to prepare AD model,randomly divided into sham group,model group,Aβ_(1~42)(0.015),0.050 mg/kg,0.150 mg/kg group and insulin group.The cognitive function of mice was detected by step-down test;the content of INR in hippocampus was detected by ELISA;the expression of p-PKB,p-GSK-3βand p-Tau proteins in the hippocampus of mice were detected by Western blot.Results Compared with sham group,the number of practice errors and memory errors was increased,and the latency was shortened(P<0.05)in model group;compared with model group,the number of practice and memory errors was increased,and the latency was shortened(P<0.05)in different doses groups of Aβ_(1~42),while the number of practice and memory errors was decreased,and the latency was increased(P<0.05)in insulin group.Compared with sham group,the expression of INR in model group was decreased(P<0.05).Compared with model group,the expression of INR in different dose groups of Aβ_(1~42)was decreased(P<0.05),and the expression of INR in insulin group was increased(P<0.05).Compared with sham group,the expression of p-PKB and p-GSK-3βprotein in model group was decreased,and the expression of p-tau was increased(P<0.05).Compared with model group,the expression of p-PKB and p-GSK-3βin different doses groups of Aβ_(1~42)was decreased,and the expression of p-tau was increased(P<0.05);the expression of p-PKB and p-GSK-3βin insulin group was increased,and the expression of p-tau was decreased(P<0.05).Conclusions Aβ_(1~42)could induce neurotoxicity and cognitive impairment in mice.The mechanism may be as follows:interference with PI3K/PKB signaling pathway,down-regulating the expression of INR,inhibiting the phosphorylation of PKB and GSK-3β,increasing the phosphorylation of tau protein in AD mice,leading to cognitive dysfunction.